today I’m trying to understand the use of these two calls … but I really can not, the description is too synthetic … can someone help me to understand adding an explanation or better some examples? Thank you very much

In the example @GunnerTechTools gives, it seems that request.pin returns the pin that triggered the BLYNK_WRITE_DEFAULT() callback:

BLYNK_WRITE_DEFAULT() {
int pin = request.pin; // determines what vPin is triggering this response
if (param.asInt() == 1) {
Serial.print("Button on Virtual Pin ");
Serial.print(pin); // Display the number of the vPin
Serial.println(" is pressed");
} else {
// Do something, or nothing, when button is OFF
}
}

so if you had different code that ran for V200, V201, V202 then you’d need to use a series of ‘if’ statements, or a Select Case statement.

But @GunnerTechTools s using request.pin to discover which pin triggered the callback. He happens to be storing it in an integer called pin, but it seems to me that it’s the request.pin keyword that’s the critical part.
As I said, I’ve never used it, and not tested either bits of code so I could be wrong.

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We’ve already shown you that the solution is to use BLYNK_WRITE_DEFAULT() instead of BLYNK_WRITE(V200), and that request.pin will return the number of the pin that triggered the BLYNK_WRITE_DEFAULT callback.

We’ve already shown you that the solution is to use BLYNK_WRITE_DEFAULT() instead of BLYNK_WRITE(V200) , and that request.pin will return the number of the pin that triggered the BLYNK_WRITE_DEFAULT callback.